It's been quite some time since Rdio's first and second Hack Days but the engineering team gathered again to create some wild and wonderful hacks using the Rdio API. This third Hack Day produced some awesome results — ranging from social features like compatibility scores to handy hacks like playlist cleanup. Here’s a brief summary from the team of some of the projects they created.

API HACKS

The Rdio API enables music enthusiasts to invent great, new ways for listeners to discover, collect, share and play music. These hacks generally don’t require any privileged insider information about Rdio. Find more info about the Rdio API here.

iOS Collection BrowserIan Gilman created an alternative Collection browsing view that works on the iOS web browser. It displays album art for the items in your Collection and provides a means to sort them. Selecting an album launches the Rdio app and plays the album. Try it for yourself here.

Weather Generated PlaylistChris Beale made a playlist integration with the Rdio API and The Echo Nest data to create mood-based playlists derived from the current weather and temperature.

FiltrotronRyan Nordman wrote a playlist control application. The app helps you manage a large playlist of new music by providing buttons that allow you to move tracks into a favorites playlist or delete them. The app is accessible here.

DiscoversongEugene Efremov added new features for his Discoversong Rdio app built with the API. Discoversong works by integrating Shazam, SoundHound, MusiXmatch, VCast SongID, or Sony Ericsson TrackID to identify a song and connect with Rdio to add the track to a playlist. The hack was built by sending a digestible email that would then use Rdio’s API to search for an Rdio library match and add it to your playlist. Try it now.

Recently Played Artists GraphAlex Gaynor's app graphs the relative amount of time you spent listening to each played artist in the past few days. Enter your username and check it out for yourself.

Playlist CleanupRaul Agrait created a cleanup tool that will scour your playlists for Rdio tracks that may be unavailable in your region, and quickly provide a search method that lets you find other versions of the track to replace it.

Concert ListingsNetta Marshall from Rdio’s design team and Anthony Taranto from the mobile team collaborated on a feature that displays concert listings based on artists in your Collection and Heavy Rotation.

SOCIAL FEATURES

Rdio is better with friends so here are some hacks that were created by Rdio engineers to add functionality into the social aspects of our service.

Sharing UsersJulia Chavez created a feature that allows you to share user profiles in a similar way you share songs and albums with your friends on Rdio. This lets you suggest influential people that you think your friends would enjoy following.

Employee SectionJason Norris added an employee section to the user profile data in Rdio accounts so that Rdio could double as an internal employee directory.

Last.fm and Compatibility ScoresLast.fm stores your listening history which can be computed into a music taste compatibility score. Joshua Uziel created an integration with Last.fm to display compatibility scores between you and users you follow, as well as a way to recommend new users to follow based on Collection similarities.

Who to Follow Using Heavy Rotation
Rdio is even better if you follow people with similar taste in music. Drew Bazan wrote a code to look through all the albums in your Heavy Rotation and suggest the albums' top listeners for you to follow.

Heavy Rotation GroupsCraig Kimerer added a new feature to group users you follow into separate Heavy Rotation views. You can put people who are inclined to certain genres of music together. — for example, create a jazz group or bucket all your angsty emo friends together to stop polluting your Heavy Rotation!

MOBILE HACKS

Rdio lets you take your music anywhere by using our mobile apps. The following hacks were created for our mobile applications.

Sending Remote ControlBrett Duncavage and Adam Lickel utilized the remote control feature, which allows you to control the Rdio app on a computer with a mobile device, and vice versa. They tweaked the feature so that you can send the music playing from the device in your hand to another device without having to move an inch.

Reordering Playlist Contents on Mobile
Taylor Perkins added a feature to Rdio for Android that allows you to reorder the contents of your playlists from the mobile app.

MISCELLANEOUS HACKS

The creations below are some handy hacks that make for a slick Rdio experience.

Log Viewer With SentryJames Cline worked on a practical hack for Rdio's engineering team. He integrated Rdio into Sentry's log in, a tool that allows you to group, sort, and filter log messages for easy viewing.

Lyrics Display
No more misheard song lyrics: Adam Polselli, from Rdio’s design team, mashed up a song lyrics display into the Rdio web app.

Notification ToastMatt Carroll added notification pop-ups to the Rdio web player so that you get a confirmation message which slowly fades out whenever you add an item to a playlist or your Collection.

Rdio Links in Web ReviewsLeslie Chong wrote a Greasemonkey script to insert Rdio links into web articles. When looking at music reviews on an external site, you can click on any of the conveniently placed links to listen to the artist or album in Rdio at the same time.